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Old 9th July 2014, 03:16 PM   #1001
fdlsys is offline fdlsys  South Africa
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Quote:
Originally Posted by bolserst View Post
Look at the schematic Tyu attached in post#996:
I have only heard of the 3+13 and 6+10 C-mods, that's what I was referring to.
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Old 9th July 2014, 03:18 PM   #1002
tyu is offline tyu  United States
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I (don't )think it makes any sonic difference. ...good luck with that...
hehe.... well it dose at my house....sonic differenes are all i am into... from good to better...best sound,now,today......
I have had Acoustats for over 30 years.... droping of the bias feed Res is the best thing i have ever done....for best output an a topend..
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Old 9th July 2014, 05:38 PM   #1003
fdlsys is offline fdlsys  South Africa
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Quote:
Originally Posted by tyu View Post
I have had Acoustats for over 30 years....
Heck! I've been married for almost as long and I still don't understand women! Don't know how to build them, fix them or improve them. Even day to day maintenance is ... unpredictable ...
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Old 9th July 2014, 06:13 PM   #1004
kouiky is offline kouiky  United States
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Quote:
Originally Posted by MrAcoustat View Post
No confusion i know Sound Lab very well they are miles ahead of Martin Logan, i am not saying that Sound Lab isn't good what i am saying is that the DIY Acoustat Spectra 8800s would hold it's own agains't ANY model of Sound Lab at even 5 times the price the reason for this is the way they are built please note that this panel weighs 800 pounds this is a very very ridgid frame compared to Sound Lab Ultimate Series U-1PX at only 272 pounds.

PS: To be honest i have not heard the 922 series but still i would not worry that's how good the Spectra 8800s are the U-1PX is good but no match not even close.
That sounds more like bias and wishful thinking based on unproven hopes. Believing something without actually testing it is the forerunner to fiction. The fact of the matter is that Sound Labs have notable advantages over the Acoustat's that allow them to perform with relative ease, notably in the bass regions; they perform better not because of any local technician building them, but because of better engineering practices. The reasons reside in the constant evolution of their design, the engineering principles, and finally the execution. Sound Labs utilize smaller panels, each hand made to exacting tolerances. The reason for these small panels is to reduce mass and structure-borne resonance. Each panel is crafted to offer the best transient response, working in unison to produce a wavefront large enough to offer low frequency extension. The long panels of the Acoustat Spectra 8800 cannot match the settling times, nor the essential freedom from resonance simply as a function of their dimensions.

Curved panels introduce a variety of problems. When Sanders designed for Martin Logan, he and I among others identified that the diaphragm would sag between the curved spacers. This had a profound effect on the transient response and cumulative spectral results, as the excursion of the diaphragm was far from linear. The answer was to retain a flat panel where good transient impulse response and fast settling were primary performance constituents. It also helped in lowering harmonic distortion which, contrary to popular brief, actually plagues electrostatics at low frequencies. The problem with flat panels was that their collective radiation planes produced a beaming polar response, making it hard for listeners to hear all the treble information when they were seated off axis. Sound Lab curtailed this problem but using neither flat panels, nor curved panels. Instead flat panels arranged in a curved pattern. Today, this represents the best possible implementation of the panel topologies. It allows the panels to be ideally shaped, the collective speaker to be as large as needed, and the polar response to be less like conventional panels and instead comparable to that of electrodynamic coil drivers - wide and heard from all angles, and close to the sound of a real acoustic event.

The Acoustat's are not bad at all, but they are a product of the past and the limited understanding of diaphragm resonance, on part of Dr. Strictland's original design team. The computer modelling was not feasible at the time that we have now, and it's quite easy to model panels before they go into testing and production. Acoustat stuck to long panels with dimensions that not only harbor modes, but actually introduce them. These show up in the transfer magnitude graphs as sharp peaks and dips. When performing an impulse response test on the Accoustat's, you'll notice they initially settle quite well, but them the delayed reflections from the panel edges return to the center. At certain frequencies, the coincidence of these reflections induce modes and cancellations. The result is both slight coloration induced by the energy storage and deviation from a linear frequency response. What is important is to view an unweighted frequency response measurement, as heavy weighting and windowing will obscure the results and hide the flaws that exist. most panel speakers demonstrate this behavioral trait.

Many of the people who are rebuilding these Acoustat panel speakers do not have a background in loudspeaker design, nor product development. I know who Josclyne from Quebec is, and while he has the initiative to go forth and rebuild these speakers, so do many others. The inherent problem in their methods is that they do not have a suitable engineering background to devise any improvements that offer tangible performance beyond the obvious. Along with this, they do not have the proper testing apparatus and environment to provide their customers with reliable data regarding the alterations. This quintessential scenario is not unlike one bringing his car to a shop for modifications to try and make it a track car. A bigger engine and stronger gear-train will improve performance, but that is not engineering, nor advancement. It is highly predicable that reinforcing the frame will reduce sway and vibration, but it fails to identify the underlying causes. Because of this, it is not really a cumulative solution.

On the other hand, Sound Lab employs the equipment needed to idealize their product before it reaches the market. It is a family business, with even the wife and children taking part in the construction affairs. The values and sizing were not random, but the product of the evolution of panel speaker design. They have the capitol to fully test their product so that it meets the most discerning standards. The only ones that none of their scientific mediums can satisfy are, or course, those of bias, pandery, and blatant misinformation just as we find on the internet today.

Click the image to open in full size.

Last edited by kouiky; 9th July 2014 at 06:42 PM.
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Old 9th July 2014, 06:16 PM   #1005
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Quote:
Originally Posted by fdlsys View Post
Heck! I've been married for almost as long and I still don't understand women! Don't know how to build them, fix them or improve them. Even day to day maintenance is ... unpredictable ...
I have been with Acoustat's for over 30 years and with my wife for 45 years and still don't know how to modify neither one of them.
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Old 9th July 2014, 06:40 PM   #1006
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Quote:
Originally Posted by kouiky View Post
That sounds more like bias and wishful thinking based on unproven hopes. Believing something without actually testing it is the forerunner to fiction. The fact of the matter is that Sound Labs have notable advantages over the Acoustat's that allow them to perform with relative ease, notably in the bass regions; they perform better not because of any local technician building them, but because of better engineering practices. The reasons reside in the constant evolution of their design, the engineering principles, and finally the execution. Sound Labs utilize smaller panels, each hand made to exacting tolerances. The reason for these small panels is to reduce mass and structure-borne resonance. Each panel is crafted to offer the best transient response, working in unison to produce a wavefront large enough to offer low frequency extension. The long panels of the Acoustat Spectra 8800 cannot match the settling times, nor the essential freedom from resonance simply as a function of their dimensions.

The Acoustat's are not bad at all, but they are a product of the past and the limited understanding of diaphragm resonance, on part of Dr. Strictland's original design team. The computer modelling was not feasible at the time that we have now, and it's quite easy to model panels before they go into testing and production. Acoustat stuck to long panels with dimensions that not only harbor modes, but actually introduce them. These show up in the transfer magnitude graphs as sharp peaks and dips. When performing an impulse response test on the Accoustat's, you'll notice they initially settle quite well, but them the delayed reflections from the panel edges return to the center. At certain frequencies, the coincidence of these reflections induce modes and cancellations. The result is both slight coloration induced by the energy storage and deviation from a linear frequency response. What is important is to view an unweighted frequency response measurement, as heavy weighting and windowing will obscure the results and hide the flaws that exist. most panel speakers demonstrate this behavioral trait.
Dear sir you are talking about something that you have never heard, this i know as FACT because there is only ONE existing pair of modified Acoustat Spectra 8800s, they where built in 2013-2014 by Jocelyn Jeanson of Quebec Canada, measured bass output without subs is 24hz but for my friend that is still not enough, the addition of two JL,s F-112 subwoofers give's them a measured bass output of 14hz the older Acoustat's of the 90s where very good for the money but these are 23 years later and are one of a kind.
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Old 9th July 2014, 06:46 PM   #1007
kouiky is offline kouiky  United States
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I am afraid that you are talking about something that you have never heard. If you had taken the time to read my post, you would have seen that I was familiar with Jocelyn and his work. I am also familiar with others who have had to correct his mistakes. Look up, way up.
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Old 9th July 2014, 06:57 PM   #1008
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Quote:
Originally Posted by kouiky View Post
I am afraid that you are talking about something that you have never heard. If you had taken the time to read my post, you would have seen that I was familiar with Jocelyn and his work. I am also familiar with others who have had to correct his mistakes. Look up, way up.
Please feel free to give names or for me these so call mistakes don't exist, for ME the only thing that counts is the result how the speakers SOUND screw the engineering if the speakers don't sound good.
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Last edited by MrAcoustat; 9th July 2014 at 07:03 PM.
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Old 9th July 2014, 08:09 PM   #1009
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Quote:
Originally Posted by Thinker1920 View Post
Hi everyone,

I just bought a pair of Acoustat model 3's with 121 interfaces, and I replaced the binding posts and did the c mod with all metallized polypropylene caps. My main listeners are magnepan mg III's and I was hoping to replace them with the acoustats since the acoustats are so sturdy, but I find the soundstage to be distant instead of in the room and the top end seems rolled off. Is there anyway to make them sound more up front and extend the top end?

Thanks :-)
Acoustats have been criticized for a slightly rolled-off top end, so they may have a little less 'sparkle' than other speakers that you've heard. However, there is a High Frequency Balance control inside the interface that can be used to change the extreme top-end response. Have you tried adjusting that control in the 'plus' direction?

Your choice of amplifier can also have some bearing on frequency response. If your amplifier has an output impedance that varies considerably with frequency, it can introduce variations in the acoustic frequency response. Nothing magic going on here - just Ohm's Law.

The imaging characteristics are often a function of speaker placement. Speaking in very general terms, the speakers seem to work best when toed-in toward the listening position, such that the plane of each speaker is perpindicular to the line of sight of the listener. Best results are usually obtained with the speakers and listener arranged in an equilateral triangle. That is, the distance between speakers should be roughly equal to the distance from each speaker to the listener. The particulars of your room acoustics and adjacent walls and furnture may require some modification of these general guidelines. But I have never encountered a situation where these guidelines do not at least provide a very good starting point.
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Old 9th July 2014, 08:23 PM   #1010
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Firstly, do you have any affiliation with Sound Lab of which you speak so highly?
Quote:
Originally Posted by kouiky View Post
The problem with flat panels was that their collective radiation planes produced a beaming polar response, making it hard for listeners to hear all the treble information when they were seated off axis. Sound Lab curtailed this problem but using neither flat panels, nor curved panels. Instead flat panels arranged in a curved pattern. Today, this represents the best possible implementation of the panel topologies.
What about segmentet panels (like in the Spectra's but with slimmer treble segment)?
Quote:
Originally Posted by kouiky View Post
It is highly predicable that reinforcing the frame will reduce sway and vibration, but it fails to identify the underlying causes. Because of this, it is not really a cumulative solution.
Not sure what you mean by this. Are you saying that stabilizing the frame is not a worthwhile modification?
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